Piezoelectric identification device and applications thereof

ABSTRACT

Provided is a transducer having first and second surfaces including first electrode lines positioned along the first surface in a first direction and configured for grounding and second electrode lines positioned along the second surface in a direction orthogonal to the first direction. The second electrode lines are configured switching between receiving and transmitting in an interlaced manner.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a piezoelectricidentification device and applications thereof.

2. Background Art

Biometrics are a group of technologies that provide a high level ofsecurity. Fingerprint capture and recognition is an important biometrictechnology. Law enforcement, banking, voting, and other industriesincreasingly rely upon fingerprints as a biometric to recognize orverify identity. See, Biometrics Explained, v. 2.0, G. Roethenbaugh,International Computer Society Assn. Carlisle, Pa. 1998, pages 1-34(incorporated herein by reference in its entirety).

Optical fingerprint scanners are available which detect a reflectedoptical image of a fingerprint. To capture a quality image at asufficiently high resolution, optical fingerprint scanners require atminimum optical components (e.g., lenses), an illumination source, andan imaging camera. Such components add to the overall cost of afingerprint scanner. Mechanical structures to maintain alignment alsoincrease manufacturing and maintenance costs.

Solid-state silicon-based transducers are also available in fingerprintscanners sold commercially. Such silicon transducers measurecapacitance. This requires the brittle silicon transducers to be withina few microns of the fingerprint sensing circuit reducing theirdurability. To detect a rolled fingerprint, the sensing array of thesolid-state transducer needs to have an area of 1 inch.times.1 inch anda thickness of about 50 microns. This is a big geometry for silicon thatincreases the base cost of a fingerprint scanner and leads to greatermaintenance costs. Durability and structural integrity are also morelikely to suffer in such a large silicon geometry.

What is needed is an inexpensive, durable fingerprint scanner with lowmaintenance costs. What is also needed is a low cost biometric devicethat can protect the individuals and the general populace againstphysical danger, fraud, and theft (especially in the realm of electroniccommerce).

BRIEF SUMMARY OF THE INVENTION

Consistent with the principles of the present invention as embodied andbroadly described herein, the present invention includes a transducerhaving first and second surfaces including first electrode linespositioned along the first surface in a first direction and configuredfor grounding and second electrode lines positioned along the secondsurface in a direction orthogonal to the first direction. The secondelectrode lines are configured switching between receiving andtransmitting in an interlaced manner.

Further features and advantages of the present invention, as well as thestructure and operation of various embodiments of the present invention,are described in detail below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate the present invention and, togetherwith the description, further serve to explain the principles of theinvention and to enable a person skilled in the pertinent art to makeand use the invention.

FIG. 1 illustrates a piezoelectric identification device according to anembodiment of the invention.

FIG. 2 illustrates a piezoelectric element according to an embodiment ofthe invention.

FIG. 3 illustrates a row of piezoelectric elements according to anembodiment of the invention.

FIG. 4 illustrates an array of rectangular piezoelectric elementsaccording to an embodiment of the invention.

FIG. 5 illustrates an array of circular piezoelectric elements accordingto an embodiment of the invention.

FIG. 6 illustrates a row of rectangular piezoelectric elements having afill material between elements according to an embodiment of theinvention.

FIGS. 7A and 7B illustrate sensor arrays according to embodiments of theinvention.

FIG. 8 illustrates a more detailed view of the sensor array of FIG. 7A.

FIG. 9 illustrates how the sensor array of FIG. 8 is connected to anapplication specific integrated circuit.

FIG. 10 illustrates how to connect a sensory array to multiplexersaccording to an embodiment of the invention.

FIG. 11 illustrates an identification device according to an embodimentof the invention.

FIG. 12 illustrates circuit components of an identification deviceaccording to an embodiment of the invention.

FIG. 13A illustrates how to apply an input signal to the sensor array ofFIG. 12 and receive an output signal from the sensor array according toan embodiment of the invention.

FIG. 13B illustrates how to control the switches of FIG. 13A accordingto an embodiment of the invention.

FIG. 14 illustrates an example voltage sensing circuit according to anembodiment of the invention.

FIG. 15 illustrates how to minimize cross-talk in a sensor arrayaccording to an embodiment of the invention.

FIG. 16 is a flowchart of a method according to an embodiment of theinvention.

FIG. 17 illustrates using an identification device to obtain biometricinformation according to an embodiment of the invention.

FIG. 18 illustrates an identification device wake-up circuit accordingto an embodiment of the invention.

FIG. 19 illustrates the impedance of a piezoelectric element loaded by afingerprint valley according to an embodiment of the invention.

FIG. 20 illustrates the impedance of a piezoelectric element loaded by afingerprint ridge according to an embodiment of the invention.

FIG. 21 illustrates a sensor array input signal according to anembodiment of the invention.

FIG. 22 illustrates a sensor array output signal according to anembodiment of the invention.

FIG. 23 illustrates how an identification device is used to obtainbiometric information according to an embodiment of the invention.

FIG. 24 illustrates how an identification device is used to obtain abone map according to an embodiment of the invention.

FIG. 25 illustrates a transmitting and/or receiving beam directivityaccording to an embodiment of the invention.

FIG. 26 illustrates how an identification device is used to obtainarteriole blood flow information according to an embodiment of theinvention.

FIG. 27 illustrates a transmitting beam directivity and a receiving beamdirectivity according to an embodiment of the invention.

FIG. 28 illustrates a transmitting and/or receiving beam directivityaccording to an embodiment of the invention.

FIG. 29 illustrates how an identification device is used to obtaincapillary blood flow information according to an embodiment of theinvention.

FIG. 30 illustrates a transmitting and/or receiving beam directivityaccording to an embodiment of the invention.

FIG. 31 is a flowchart of a method according to an embodiment of theinvention.

FIG. 32 illustrates a biometric device according to an embodiment of theinvention.

FIG. 33 illustrates a mobile biometric device according to an embodimentof the invention.

FIG. 34 illustrates a wireless transceiver biometric device according toan embodiment of the invention.

FIG. 35 illustrates a more detailed view of the wireless transceiverbiometric device of FIG. 34.

FIG. 36 illustrates using the wireless transceiver biometric device ofFIG. 34 to complete an electronic sales transaction.

FIG. 37 illustrates various applications for the wireless transceiverbiometric device of FIG. 34.

FIG. 38 illustrates a wireless transceiver biometric device according toan embodiment of the invention.

FIG. 39 is a diagram of an example piconet having coupling BLUETOOTHdevices with a public service layer.

FIG. 40 is an illustration of an interlaced transmit/receive transducer.

FIG. 41 is an illustration of a single line swipe fingerprint sensorarray constructed in accordance with an embodiment of the presentinvention.

FIG. 42 is an illustration of an N×M swipe fingerprint sensor arrayconstructed in accordance with another embodiment of the presentinvention.

FIG. 43 is an illustration of pillar damping as performed in anembodiment of the present invention.

FIG. 44 is an illustration of an aperture configured for biplane imagingin accordance with an embodiment of the present invention.

FIG. 45 is an illustration depicting linear electronic switching scansin an azimuthal direction in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Table of Contents I. Overview of the Invention II. Example Devises andSystems According to the Invention

A. Piezo Ceramic Sensors

B. Piezo Film Sensors

C. Sensor Array Address Lines

D. Example Identification Device

E. Example Multiplexer III. Example Methods According to the Invention

A. Impedance Mode

B. Attenuation/Voltage Mode

C. Doppler-Shift and Echo Modes IV. Example Application of the Invention

A. Biometric Capture Device

B. Mobile Biometric Capture Device

C. Wireless Transceiver Biometric Device

D. Electronic Sales and/or Transactions

E. Other Wireless Transceiver Biometric Device Applications

F. Personal Area Network Applications

G. Public Service Layer Applications

I. Overview of the Invention

The present invention relates generally to a piezoelectricidentification device and applications thereof. More particularly, itrelates to a piezoelectric device for obtaining biometric data orinformation, such as a fingerprint, and using the obtained informationto recognize and/or yen the identity of an individual.

II. Example Devises and Systems According to the Invention

FIG. 1 is a schematic diagram of a piezoelectric identification device100 according to an embodiment of the invention. Identification device100 has a piezoelectric sensor 100, a sensor input signal generator 120,a sensor output signal processor 130, and a memory 140. The input signalgenerated by input signal generator 120 is coupled to sensor 110 by twomultiplexers 150. The output signal of sensor 110 is similarly coupledto output signal processor 130 by two multiplexers 150.

A. Piezo Ceramic Sensors

Sensor 110 is preferably an array of piezo ceramic elements. Forexample, sensor 110 can comprise an array of polycrystalline ceramicelements that are chemically inert and immune to moisture and otheratmospheric conditions. Polycrystalline ceramics can be manufactured tohave specific desired physical, chemical, and/or piezoelectriccharacteristics. Sensor 110 is not limited to comprising an array ofpiezo ceramic elements, however. Sensor 110 can comprise, for example, apiezoelectric film. A polarized fluoropolymer film, such as,polyvinylidene flouride (PVDF) film or its copolymers can be used.

FIG. 2 illustrates the operating characteristics of a single rectangularpiezo ceramic element 200 having surfaces 210, 220,230, and 240. Whenforce is applied to surfaces 210 and 220, a voltage proportional to theapplied force is developed between surfaces 210 and 220. When thisoccurs, surfaces 230 and 240 move away from one another. When a voltageis applied to surfaces 210 and 220, surfaces 230 and 240 move towardsone another, and surfaces 210 and 220 move away from one another. Whenan alternating voltage is applied to surfaces 210 and 220, piezo ceramicelement 200 oscillates in a manner that would be known to a personskilled in the relevant art.

FIG. 3 illustrates a row of five rectangular piezo ceramic elements200A, 200B, 200C, 200D, and 200E. Each of these rectangular piezoceramic elements 200 is attached or integral to support 302. Support 302inhibits the movement of one surface of each rectangular piezo ceramicelements 200. Thus, when an alternating voltage is applied to surfaces210 and 220 of piezo ceramic element 200C, a sonic wave is generated atsurface 210 of piezo ceramic element 200C. The frequency of thegenerated sonic wave is dependent on the physical characteristics ofpiezo ceramic element 200C.

FIG. 4 illustrates a two-dimensional array 400 of rectangular piezoceramic elements 200. Array 400 can be made from lead zirconate titanate(PZT). PZT is an inexpensive material. In an embodiment array 400 issimilar to a PZT 1-3 composite used in medical applications. The piezoceramic elements of sensor 110 according to the invention can haveshapes other than rectangular. As illustrated in FIG. 5, sensor 110 cancomprise an array 500 of circular piezo ceramic elements.

In a preferred embodiment, array 400 comprises rectangular piezo ceramicelements that are 40 microns square by 100 microns deep, therebyyielding a 20 MHz fundamental frequency sonic wave. A spacing of 10microns is used between elements in this embodiment in order to providea 50-micron pitch between elements. A pitch of 50-micron enables anidentification device according to the invention to meet the FederalBureau of Investigation's quality standards for fingerprints. Otherembodiments of the invention use geometries different than the preferredembodiment. For example, a pitch of greater than 50 microns can be used.Other embodiments also operate a frequencies other than 20 MHz. Forexample, embodiments can operate at frequencies of 30 Mhz and 40 MHz, inaddition to other frequencies.

As shown in FIG. 6, the spacing between the elements of a sensor arrayaccording to the invention can be filled-in with a flexible typematerial or filler 602 to suppress any shear waves and give the sensorimproved mechanical characteristics. Micro-spheres 604 can be added tothe filler 602 (e.g., vinyl micro-spheres) to reduce weight and/orincrease the suppression of shear waves. In order to optimize thesignal-to-noise ratio of an identification device, and the devicesensitivity, fillers (e.g., araldite filled with air filled vinylmicro-spheres) that provide high acoustical attenuating and electricalisolation should be used.

At least four fabrication methods exist for producing array 400. Thesemethods include: laser cutting, dicing, molding, and screen-printing.Laser cutting involves using an excimer laser to cut small groves andthereby form the elements of array 400. Dicing involves using highperformance dicing equipment to form groves and the elements of array400. Molding involves using injection molding equipment to form array400. Screen-printing is a technique similar to that of solder printingin the assembly of printed circuit boards, where highly automated screenprinting machines are adapted with laser cut stencils. This method isparticularly suited to producing 20 MHz sonic wave elements since theceramic elements are only 100 microns thick. This method involvesproducing a ceramic slurry of appropriate consistency, and has theadvantage of not requiring surface grinding as may be required with themolding method.

FIG. 7A illustrates a sensor array 700 comprising rectangular piezoceramic elements according to a preferred embodiment of the invention.Sensor array 700 is a multilayer structure that includes atwo-dimensional array of rectangular piezo ceramic elements 200, similarto array 400. Conductors (such as conductors 706 and 708) are connectedto each of the rectangular piezo ceramic elements 200. The conductorsconnected to one end of each element 200 (e.g., conductor 706) areoriented orthogonal with respect to the conductors connected to anotherend of each element 200 (e.g., conductor 708). A shield layer 702 can beadded to one side to provide a protective coating where a finger can beplaced proximate to sensor array 700. A support 704 can be attached tothe opposite end of the sensor array. Sensor array 700 is described inmore detail below.

B. Piezo Film Sensors

FIG. 7B illustrates a sensor array 750 comprising piezoelectric film(piezo film) according to an embodiment of the invention. FIG. 7B is across-sectional view of sensor array 750. Sensor array 750 is amulti-layer structure that includes a piezoelectric layer 752 sandwichedby two conductor grids 754 and 756. Conductor grids 754 and 756 eachconsist of rows of parallel electrically conductive lines. Preferably,the lines of grid 754 are oriented orthogonal with respect to the linesof grid 756 (that is, in x and y directions, respectively). Thisorientation creates a plurality of individually addressable regions orelements in the piezo film. As used herein, the term element refers toany region of a sensor array that can be addressed, either individuallyor as part of a larger region, using the rows of parallel electricallyconductive lines (conductors). Piezoelectric polymer film sensors arefurther described in Piezo Film Sensors: Technical Manual, availablefrom Measurement Specialities, Inc. Norristown. Pa., Apr. 2, 1999 REVB(incorporated by reference herein in its entire).

Shield layer 758 can be added to one side where a finger is placed toprovide a protective coating. Foam substrate 760 can be used as asupport. As shown in FIG. 7B, the multiple layers of sensor array 750are stacked along one direction (e.g., a z-direction).

In an embodiment, piezo layer 752 is a polarized fluoropolymer film,such as, polyvinylidene flouride (PVDF) film or its copolymers.Conductor grids 754 and 756 are silver ink electrodes printed onopposite sides of the PVDF film 752. Shield layer 758 is made ofurethane or other plastic. Foam substrate 760 is made of TEFLON. Anadhesive 762, 764 holds shield layer 758 and foam substrate 760 onopposite sides of the printed PVDF film 752 as shown in FIG. 7B.

In an embodiment, the PVDF film, including the printed electrodes, canbe peeled off like a label for easy replacement. As shown in FIG. 7B,sensor array 750 can be mounted by adhesive 766 onto wax paper or othermaterial (not shown) for easy peel off. This allows the piezo sensor tobe installed and/or replaced simply and easily at minimum cost. Comparedto optical and silicon technologies, maintenance of the piezo sensorarray 750 is trivial.

C. Sensor Array Address Lines

FIG. 8 illustrates a more detailed view of sensor array 700. Asdescribed above, sensor array 700 comprises piezo ceramic elementshaving an filler 602. Filler 602 preferably contains micro-spheres 604.This structure is then sandwiched between several layers. This centralcomposite layer is an active structure that can be used, for example, tomap fingerprint mechanical impedances into a matrix of electricalimpedance values.

Each rectangular piezo ceramic element 200 of sensor array 700 isconnected to two electrode lines (e.g., conductors 706 and 708). Theelectrode lines on one end of sensor array 700 run perpendicular to theelectrode lines on opposite end of sensor array 700. Thus, any singleelement 200 of the array can be addressed by selecting the two electrodelines connected to it. The electrode lines are preferably created byvacuum despoliation and lithography, and they are connected to theswitching electronics via an interconnect technique described below.

On top of the one set of electrode lines is a protection layer 702.Protective layer 702 is preferably made of urethane. This protectinglayer is intended to be in contact with a finger during operation of thesensor.

A support 704 or backing layer serves as a rear acoustical impedance foreach of the rectangular piezo ceramic elements 200. In a preferredembodiment, support 704 is made of TEFLON foam. In order to provide alarge variation of the electrical impedance of an element when loadedand unloaded, the acoustical impedance support 704 should beacoustically mismatched to the sensor element material. Either a verylow or a very high acoustic impedance material can be used. Forembodiments using piezo ceramic materials, the preferred impedancemismatch can be obtained by an air backing rather than by a hardbacking. This is because the sensor has a high acoustic impedance.

The materials described herein for constructing sensor array 700 areillustrative and not intended to limit the present invention. Othermaterials can be used, as would be known to a person skilled in therelevant art.

FIG. 9 illustrates how sensor array 700 can be connected to anapplication specific integrated circuit. As described herein, anindividual piezo ceramic element (m, n) of sensor array 700 can beaddressed by selecting (addressing) conductor m on the top of sensorarray 700 and conductor n on the bottom of sensor array 700. Otherconductors can be either grounded or open (high impedance state),particularly those conductors used to address elements in theneighborhood of the element being selected, in order to reducecross-talk. Parasitic currents in the neighborhood of the selectedelement are minimized mechanically by the interstitial filler 602,described above with regard to FIGS. 6 and 7A. Since in the preferredembodiment, the spacing between elements (pitch) is about 50 microns andstandard bonding technologies require a pitch of about 100 microns,alternate rows on an “East” and “West” and alternate columns on a“North” and “South” sides of sensor array 700, as shown in FIG. 9,connect the sensor to the “outside world”. As shown in FIG. 9, Theseconductors can be terminate in a “Bump” technology around three edges908 of an ASIC multiplexer 902. In an embodiment, side 908 of ASICmultiplexer 902 is about 3 mm.

In an embodiment, ASIC multiplexer 902 is connected to a high densityflex 906. High density flex 906 is connected to an epoxy substrate 904.Conductors can be formed or attached to the high flex to couple theconductors of the array to ASIC multiplexer 902. For example, aconductor on high density flex 906 is shown in FIG. 9 coupling conductor708 to ASIC multiplexer 902. Conductor is coupled to ASIC multiplexer902 by bump soldering. Anisotropic glue can be used to couple theconductor on high density flex 906 to conductor 708 of the sensor array.Other means for connecting and electrically coupling ASIC multiplexer902 to sensor array 700 are known to persons skilled in the relevantart, and these means also can be used in accordance with the invention.

FIG. 10 illustrates how to connect a sensory array 1002 to four ASICmultiplexers 902 according to an embodiment of the invention. Asdescribed herein, electrode lines or conductors can be vapor depositedon both sides of the substrate 902 (not shown in FIG. 10) and thenetched into the desired pattern. Before the line and row pattern isetched, substrate 902 should be polarized in a manner similar to that ofmedical transducers.

A polarized substrate is connected to a socket or multi chip module casethat is compatible with available printed circuit board technologies.The piezo ceramic matrix or sensor array 1002 can be backed by an airequivalent foam or aluminum oxide. Either backing is designed tomiss-match the composite piezo material at 8 Mrayls to cause any energycoupling to occur only at the front face of sensor array 1002, where forexample a fingerprint can be scanned. It should be noted in FIG. 10 thatthe conductors on both the top and bottom of sensor array 1002 areinterleaved in the manners described above to facilitate bondingtechnologies requiring a pitch of about 100 microns.

FIG. 11 illustrates an identification device 1100 according to anembodiment of the invention. In a preferred embodiment, device 1100 hasa piezo ceramic sensor array 1102 that is physically lager enough tocapture any fingerprint placed without accuracy on sensor array 1102(e.g., about 25 mm square). Sensor array 1102 is preferably compliantwith CJIS ANSII NIST standards in resolution (500 points per 25.4 mm),and it has a pixel dynamic range sufficient to provide 256 distinctshades of gray.

As show in FIG. 11, in an embodiment, substrate 1110 is attached to aprinted circuit board 1104. The conductors of sensor array 1102 arecoupled to two integrated circuits 1106 and two integrated circuits1108, which couple sensor array 1102 to other circuits, which aredescribed elsewhere herein. Integrated circuit 1112 is a wirelesstransceiver that enables embodiments of the invention to communicatewith other devices as part of a personal area network. This connectivitypermits embodiments of the invention to supply, for example, a standardsecure identification and/or authorization token to any process ortransactions that need or require it. The connection scheme shown isFIG. 11 is an alternative connection scheme that can be used toimplement embodiments of the invention.

The above sensor array descriptions are illustrative and not intended tolimit the present invention. For example, piezo layer 752 can be anymaterial exhibiting a piezoelectric effect including, but not limitedto, piezoelectric polymers. Conductor grids 706, 708, 754 and 756 can beany electrically conductive material including, but not limited to,metals. Likewise, other types of protective material can be used forshield layers 702 and 758 as would be apparent to a person skilled inthe art given this description. Other types of supportive material canbe used in place of support 704 or foam substrate 760.

D. Example Identification Device

FIG. 12 illustrates an identification device 1200 according to anembodiment of the invention. Device 1200 comprises an input signalgenerator 1202, a sensory array 1220, an output signal processor 1240, amemory controller 1260, and a memory 1270. Sensor array 1220 is coupledto input signal generator 1202 and output signal processor 1240 bymultiplexers 1225A and 1225B, respectively. A controller 1230 controlsthe operation of multiplexers 1225A and 1225 B. The operation ofidentification device 1200 is further described below.

In an embodiment, input signal generator 1202 comprises an input signalgenerator or oscillator 1204, an variable amplifier 1206, and a switch1208. In a preferred embodiment, oscillator 1204 produces a 20 MHzsignal, which is amplified to either a low or a high voltage (e.g.,about 4 volts or 8 volts) by variable amplifier 1206, depending on themode in which device 1200 is operating. Switch 1208 is used to provideeither no input signal, a pulsed input signal, or a continuous waveinput signal. Switch 1208 is controlled to produce the various types ofinput signals described herein in a manner that would be known to aperson skilled in the relevant art. As shown in FIG. 12, the inputsignal generated by input signal generator 1202 is provided to sensorarray 1220, through multiplexer 1225A, and to controller 1230 and outputsignal processor 1240.

The structure and details of sensor array 1220 are explained above. In apreferred embodiment, sensor array 1220 is a piezo ceramic composite ofrectangular elements designed to operate with a 20 MHz input signal.

E. Example Multiplexer

FIGS. 13A and 13B illustrate how to apply an input signal generated byinput signal generator 1202 to the sensor array 1220, and how to receivean output signal from sensor array 1220 according to an embodiment ofthe invention. In a preferred embodiment, sensor array 1220 comprises200,000 elements 200 arranged in a two-dimensional array (i.e., a500.times.400 element array). The 500 conductors of array 1220 thatconnect, for example, to the element rows on the bottom of array 1220must be connected to input signal generator 1202, either one at a timeor in various groupings, while the 400 lines that connect to the columnson the top of the array 1220 must be connected, for example, to animpedance meter or Doppler circuit, either one at a time or in variousgroups. This task is accomplished by multiplexers 1225.

In an embodiment, multiplexers 1225 are incorporated into four identicalASICs (see FIG. 10). These four ASICs comprise analog multiplexers,amplifiers, detection circuits, and logic. In a preferred embodiment,the voltage of the input signal to sensor array 1220 is restricted toless than 8 volts, which permits the ASICs to be constructed using3-micron geometry, and to attain a switch impedance of less than 5 ohms.The four basic sections of each of these ASIC are: (1) multiplexers asdescribed herein; (2) amplifier/automatic gain controllers; (3) Dopplerdetectors; and (4) a digital signal processor (DSP) interface. Thestructure and implementation of items (2) through (4) are known topersons skilled in the relevant art.

In an embodiment, multiplexers 1225 comprise seventeen 16:1multiplexers, thus giving one output or 16 outputs as selected. Thefunction of each switch in the multiplexer is determined by a shiftregister 1302 that is 272 bits long and 2 bits wide (see FIG. 13B). Theloading and clocking of shift register 1302 is performed by controller1230, which comprises a counter and logic that would be known to aperson skilled in the relevant art. As shown in FIG. 13A, the conductorsof sensor array 1220 can be connected to either ground, signal inputgenerator 1202, or they can be unconnected (high impedance). Multiplexer1225A is designed for lowest “on” resistance. Multiplexer 1225B connectsall (256) conductors of one side of sensor array 1220 to one or sixteensense nodes. Both multiplexers 1225A and 1225B are connected to the samefunction logic (i.e, controller 1230) so that the proper sensor elementsare selected and used, for example, for voltage sensing. Element columnsand rows, in the neighborhood of an element or group of elementsselected for sensing, can be switched to ground to prevent coupling andinterference.

FIG. 13B illustrates how to control the switches of multiplexers 1225according to an embodiment of the invention. As described herein, eachswitch of multiplexer 1225 connected to a conductor of array 1220 can bein one of three states: connected to ground, connected to signal inputgenerator 1202, or open (high impedance). This can be implemented, forexample, using two CMOS gates, as shown in FIG. 14. A 272 bit long by 2bit wide shift register can then be used to control the position of eachswitch. Bits from controller 1230 are shifted into shift register 1302to control the position of the switches of multiplexers 1225. In anembodiment, shift register 1302 is coupled to the switches ofmultiplexer 1225 using latches so that the position of the multiplexerswitches remain constant as new bits are being shifted into shiftregister 1302. How to implement this embodiment would be known to aperson skilled in the relevant art. Other means for implementing thefunctionality of multiplexers 1225 can be used without departing fromthe scope of the invention.

FIG. 14 illustrates an example voltage detector 1244 according to anembodiment of the invention. As will be understood by a person skilledin the relevant art, the voltage drop in each conductor of sensor array1220 is large compared to the voltage drop of the elements of the arraybecause all the elements coupled to a particular conductor are drawingfrom a signal source (i.e., input signal generator 1202). If eachelement has an impedance of 500 ohms, the impedance of 400 elementsconnected in parallel is 1.25 ohms. This situation can be compensatedfor, however, by using a second multiplexer to measure the true outputvoltage of the elements. As can be see in FIG. 14, multiplexer 1402 isused to move the virtual zero-point of the amplifier 1404 before theswitch of multiplexer 1406.

As explained herein, the choice of apertures, their relative position insensor array 1220, and the number of apertures intended to be operatedsimultaneously will affect the complexity of the logic of formultiplexer 1225. Thus, in a preferred embodiment, this logic isimplemented using a DSP. The mode of operation of device 1200 can beselected on the four identical ASICs described above using modeswitches. These mode switches can be used to operate switches 1250 (seeFIG. 12) to direct the output of multiplexer 1225 B to the properdetector of output signal generator 1240.

The operation of impedance detector 1242, signal time of travel detector1246, and Doppler shift detector 1248 are described below. Circuits toimplement the functionality of these detectors will be known to personsskilled in the relevant art given their descriptions herein.

The output of output signal processor 1240 is biometric data. This datacan be stored in memory 1270 using memory controller 1260. FIG. 21 is aflowchart of a method according to an embodiment of the invention. Useof this biometric data is described below.

FIG. 15 illustrates means for increasing scanning speed and minimizingcross-talk in a sensor array 1500 according to an embodiment of theinvention. As seen in FIG. 15, multiple elements can be activesimultaneously and a first means for minimizing cross-talk is toseparate geographically the active elements 1502 of array 1500. Asexplained herein, a dynamic grounding scheme (i.e., coupling theelements 1504 in the neighborhood of an active element 1502 to ground)can be used that moves with the active elements 1502 as they scan acrossthe sensor array 1500. This reduces the capacitive coupling to groundand electrical cross-talk while maintaining a Faraday Cage for allsensed frequencies. In addition, an interstitial filler can be used toreduce cross-talk and thereby the parasitic currents in the neighborhoodof the selected elements 1502. Other elements of array 1500, e.g.,elements 1506, are connected to conductors that are open.

III. Example Method Embodiments of the Invention

FIG. 16 is a flowchart of a method 1600 according to an embodiment ofthe invention. Method 1600 comprise two steps 1610 and 1620. In step1610, a biological object, for example, a finger or a hand, is placeproximate to a piezoelectric ceramic array. In step 1620, an output isobtained from the sensor array. The obtained output is processed asexplained below to obtain biometric data that can be used to recognizeor verify the identity of a person, whose finger or hand, for example,was placed proximate to the sensor array. Each of the steps 1610 and1620 are described further below with regard to the various operatingmodes of device 1200, described above.

As described herein, identification device 1200 is operated in differentmodes depending on the biometric data to be obtained. The biometric datathat can be obtained using device 1200 includes fingerprints, bone maps,arteriole blood flow, and/or capillary blood flow.

FIG. 17 illustrates using identification device 1200 to obtain afingerprint of a finger according to an embodiment of the invention. Asseen in FIG. 17, finger 1702 is place proximate to the sensor array 1220of device 1200. In a preferred embodiment, sensor array 1220 is similarto piezo ceramic sensor array 700.

Two fingerprint ridges 1704 of finger 1702 are in direct contact withprotective shield 702. A fingerprint valley (i.e., cavity) 1706 offinger 1702 is not in direct contact with protective shield 702. As canbe seen in FIG. 17, there are approximately six piezo ceramic elements200 between the adjacent fingerprint ridges 1704.

Initially, device 1200 is in a power saving mode. This mode isparticularly useful for prolonging battery life in mobile versions ofdevice 1200. When finger 1702 applies a force to sensor array 1220, awake-up circuit 1800 (see FIG. 18) operates to turn-on device 1200.

Wake-up circuit 1800 comprises a capacitor 1802, a diode 1804, and aswitch 1806. When finger 1702 applies a force to piezo ceramic elements200, a voltage is developed by the elements causing capacitor 1802 toaccumulate a charge. When enough charges has been accumulated, thevoltage so produced causes switch 1806 to be turned-on. Voltage source1808 is used to power device 1200 once switch 1806 is turned-on. Powerwill continue to be supplied to device 1200 until capacitor 1802 isdischarged using a turn-off circuit (discharging resister not shown).

After device 1200 wakes-up, device 1200 can be operated in either animpedance detection mode or an attenuation mode (voltage mode) in orderto obtain an output from sensor array 1220 that can be processed toobtain the fingerprint of finger 1702. Each of these modes are explainedbelow.

The outputs of the elements of piezo sensor 200 can be summed todetermine the centroid of the point of contact of the finger with thedevice. Any movement of the finger across the device can thus be sensedand the sensor 200 can be used as a pointing device. For example, thecentroid of a finger in contact with piezo sensor 200 can be used topoint on interconnected viewing devices. The sum of the sensors elementscan also used to determine if the user is pressing with too little ortwo much force and the result fed back to the user.

The embodiment shown in FIG. 18 can also be used as a switch to make aselection on an interconnected viewing device. For example, if ananalog-to-digital converter (not shown) is coupled to capacitor 1802,the voltage across capacitor 1802 is converted to a digital signal thatcan be used interactively to make the selection by a user. As a uservaries the pressure applied to sensor 200, the voltage across capacitor1802 will vary. The analog-to-digital converter converts this timevarying voltage, for example, to a series of numbers between 00000000(base 2) and 11111111 (base 2). The output of the analog-to-digitalconverter is periodically sampled and used to make and/or indicate aselection (e.g., the number can be input to a processor and used to makeand/or indicate a particular selection). A graphical user interface on aviewing device provides feedback to the user and indicates to the userwhich of the possible selections is being selected by the user based onthe pressure applied to sensor 200. To change a selection, the usersimply applies either more or less pressure to sensor 200.

A. Impedance Mode

FIG. 19 illustrates the impedance of a single piezo ceramic element 200loaded by a fingerprint valley 1706 according to an embodiment of theinvention. At a frequency of about 19.8 MHz, the impedance of an element200 loaded by a fingerprint valley is approximately 800 ohms. At afrequency of 20.2 MHz, the impedance is approximately 80,000 ohms. At afrequency of 20 MHz, the impedance is approximately 40,000 ohms. As canbe seen when FIG. 19 is compared to FIG. 20, both the absolute impedanceof an element 200 loaded with a fingerprint valley and the change inimpedance with frequency of an element 200 loaded with a fingerprintvalley is significantly different from that of an element 200 loadedwith a fingerprint ridge. This difference can be used to obtain anoutput from sensor array 1220 that can be processed by output signalprocessor 1240 to produce fingerprint data.

FIG. 20 illustrates the impedance of a single piezo ceramic element 200loaded by a fingerprint ridge 1704 according to an embodiment of theinvention. As can be seen in FIG. 20, at a frequency of about 19.8 MHz,the impedance of an element 200 loaded by a fingerprint ridge isapproximately 2,000 ohms. At a frequency of 20.2 MHz, the impedance isapproximately 40,000 ohms. At a frequency of 20 MHz, the impedance isapproximately 20,000 ohms. Thus, both the absolute impedance of anelement 200 loaded with a fingerprint ridge and the change in impedancewith frequency of an element 200 loaded with a fingerprint ridge issignificantly different from that of an element 200 loaded with afingerprint valley.

When operating in the impedance mode, identification device 1200determines the absolute impedance of an element 200 and/or the change inimpedance of an element 200 with frequency to determine whether a givenelement 200 is loaded by a fingerprint ridge 1704 or a fingerprintvalley (cavity) 1706. To obtain a measure of the impedance of an element200, input signal generator 1202 is used to produce low voltage pulsesthat are input to the elements of sensor array 1220 using multiplexer1225A. The output signals obtained at multiplexer 1225B are related tothe absolute impedance of the elements 200 of array 1220. These outputsignals are routed by switch 1250 to impedance detector 1242 todetermine a measure of the absolute impedances of the elements of array1220. To obtain a fingerprint, it is only necessary that impedancedetector 1242 be able to determine whether a given element 200 is loadedby a fingerprint ridge or a fingerprint valley. These determinations ofwhether a particular element 200 is loaded by a fingerprint ridge orfingerprint valley can be used to generate pixel data that representsthe fingerprint of finger 1702. The fingerprint is stored in memory1270. The fingerprint can also be transmitter to other devices asdescribed below.

If the fingerprint of finger 1702 is scanned twice using two differentinput signal frequencies, the change in the impedances of the elements200 with frequency can be calculated. As already described herein, thechange in the impedances of the elements 200 with frequency is differentdepending on whether an element 200 is loaded by a fingerprint ridge orfingerprint valley. As can be seen in FIG. 12, the input signalgenerated by input signal generator 1202 is supplied to output signalprocessor 1240. Thus, output processor 1240 can determine both thefrequency and the voltage of the signals being input to sensor array1220.

An impedance detector circuit (not shown) can be implemented using an opamp. The output of multiplexer 1225B is supplied to the negative port ofthe op amp and an amplified signal is obtained at the output port. Aswould be known to a person skilled in the relevant art, the positiveport of the op amp is coupled to ground and a resistance is placedbetween the negative port and the output port of the op amp. If theamplified voltage at the output port exceeds a predetermined thresholdvoltage, the particular element 200 being measured is loaded by afingerprint ridge. This is due to the fact that the absolute impedanceof an element 200 loaded by a fingerprint ridge (for a given frequency)is approximately half of the impedance of an element 200 loaded by afinger print valley. Thus, the voltage of the output signal provided tothe op amp from an element 200 loaded by a fingerprint ridge isapproximately twice the voltage of the output signal provided to the opamp from an element 200 loaded by a fingerprint valley.

B. Attenuation/Voltage Mode

As stated above, device 1200 can also operate in an attenuation orvoltage mode to obtain the fingerprint of finger 1702. This mode ofoperation is available whether sensor array 1220 is a piezo ceramicarray (e.g., array 700) or a piezo film array (e.g., array 750). Theattenuation mode of device 1200 is based on the principle that energyimparted to an element 200 loaded by a fingerprint ridge 1704 can betransferred to finger 1702, while energy imparted to an element 200loaded by a fingerprint valley 1706 cannot be transferred to finger1702.

In the attenuation mode, input signal generator 1202 produces a highvoltage, pulsed signal that is provided to the elements of sensor array1220 using multiplexer 1225A. FIG. 21 illustrates a one-cycle inputpulse. An input signal is typically longer than one-cycle, however. Inan embodiment, an input signal is about ten-cycles long. These inputsignal causes the elements of the array to vibrate and produce sonicwaves. These sonic waves can travel from an element through the shieldlayer to a fingerprint ridge 1704 above the element. These sonic wavescan pass into a fingerprint ridge 1704 because the acoustic impedance ofthe shield layer is matched to the acoustic impedance of finger 1702. Noacoustic barrier to the sonic waves is formed by the interface between afingerprint ridge 1704 and the shield layer. The energy imparted to anelement loaded by a fingerprint ridge is thus dissipated. In the case ofan element loaded by a fingerprint valley, the energy imparted to anelement remains trapped in the element for a longer period of time. Thisis because the air in the fingerprint valley acts as an acousticbarrier.

After a number of cycles, the voltages of output signals obtained forthe array are determined and processed to obtain the fingerprint offinger 1702. FIG. 22 illustrates an example output signal. In anembodiment, since the energy imparted to an element loaded by afingerprint ridge 1704 is dissipated more quickly that then energyimparted to an element loaded by a fingerprint valley 1706, the voltageof an output signal obtained from an element loaded by a fingerprintridge 1704 is only about 1/10th of the voltage of the input signal. Inthis embodiment, the voltage of an output signal obtained from anelement loaded by a fingerprint valley 1706 is about ½ of the voltage ofthe input signal. This difference in voltages can be detected by voltagedetector 1244 and processed to generate the fingerprint of finger 1702.A means for implementing voltage detector 1244 is described above. Othermeans will be known to a person skilled in the relevant art.

C. Doppler-Shift and Echo Modes

Identification device 1200 can be operated in at least two other modes.These modes are signal time of travel (echo) mode and Doppler-shiftmode. Echo mode can also be referred to as imaging mode. These modes areused to obtain biometric data such as bone maps, arteriole-veinal maps,arteriole blood flow and capillary blood flow, as described below.Combinations of these biometrics and/or others can also be obtained. Forexample, a ratio of arteriole blood flow to capillary blood flow can beobtained and used to indicate the emotional state or well-being of ahost.

FIG. 23 illustrates how an identification device 1200 operating in echoor Doppler-shift mode can be used to obtain biometric informationaccording to embodiments of the invention. As described herein, a highvoltage signal can be input to the elements of sensor array 1220 toproduce sonic waves. These sonic waves travel through finger 1702 andare reflected by various features of finger 1702, such as, for examplethe bone of finger 1702, the fingernail of finger 1702, or the bloodflowing in finger 1702.

FIG. 24 illustrates how an identification device 1200 is used to obtaina three-dimensional bone map according to an embodiment of theinvention. To generate a map of a bone 2402 of finger 1702, device 1200is operated in its echo mode. Sound waves traveling from the skinsurface into finger 1702 will be reflected from the bone structure ofbone 2402. This structure can be identified from the large echoamplitude that it causes. Since the echo travel time is a measure of thesensor to bone distance, a three-dimensional map of the shape of bone2402 can be attained.

To obtain a map of bone 2402, a high voltage, pulsed input signal isgenerated by input signal generator 1202 and provided to the elements ofarray 1220. This input signal causes the elements to generate sonicwaves that travel into finger 1702. As shown in FIG. 24, only certainelements 200 of array 1220 are actively generating sonic waves at anygiven time. In accordance with the invention, and as described herein,active sonic wave transmitting and receiving apertures are configuredand moved (scanned) across sensor array 1220 using controller 1230 andmultiplexers 1225. The generated sonic waves travel through finger 1702and are reflected by the structure of bone 2402. These reflected sonicwaves are then detected by the receiving apertures. The time of travelof the sonic waves are obtained by detector 1246 of device 1200 and usedto detect whether bone structure is located at a various distances fromarray 1220. As would be known to a person skilled in the relevant art,this mode of operation is similar to how radars operate.

The wavelength of the sonic waves and the aperture selected define thetransmit and receive beam shape. Various aperture sizes and beamdirectivity can be formed in accordance with the invention. FIG. 25illustrates a example beam directivity that can be used to obtain a bonemap of bone 2402 according to an embodiment of the invention. Otherbeams can also be used.

FIG. 26 illustrates how identification device 1200 is used to obtainarteriole blood flow information according to an embodiment of theinvention. An artery 2602 and capillaries 2604 are shown for finger1702. As seen in FIG. 26, arteriole blood flow is parallel to thesurface of sensory array 1220.

Arteriole blood flow data is obtained from device 1200 while it isoperating in Doppler-shift mode. To receive a Doppler-shift signalback-scattered from red blood cells flowing in artery 2602, the transmitand receive directivity beam patterns of sensor array 1220 must form oneor more overlapping volumes 2606.

FIG. 27 illustrates a transmitting aperture 2610A and a receivingaperture 2610B according to an embodiment of the invention that form anoverlapping volume 2606. One approach for creating transmittingapertures 2610A and receiving apertures 2610B is to make the aperturesless than about six wavelengths square (e.g., 300 microns or sixelements on a side) and spaced at a pitch of two wavelengths (600microns). These apertures create side beams or grating lobes at about 30degrees and form overlapping regions 2606 at a depth appropriate fordetecting arteriole blood flow. FIG. 28 illustrates a transmittingand/or receiving beam formed by such apertures according to anembodiment of the invention. Other apertures can also be used. The angleat which grating lobes can be created are controlled by the ratio of thepitch between apertures and the wavelength of the sonic waves generated,as would be known to a person skilled in the relevant art given thedescription of the invention herein.

As seen in FIGS. 26 and 27, sonic energy produced by aperture 2610A isscattered by blood cells flowing in artery 2602 and received at aperture2610B. The input signal provided to the elements of array 1220 that makeup aperture 2610A is a high voltage, continuous wave signal. This inputsignal is also provided to output signal processor 1240 as a referencesignal for Doppler-shift detector 1248. This input or reference signalis mixed by Doppler-shift detector 1248 with the output signal receivedfrom aperture 2610B to obtain Doppler-shift information. Circuits forimplementing Doppler-shift detector 1248 are known in the relevant art,and thus not reproduced here.

FIG. 29 illustrates how an identification device 1200 is used to obtaincapillary blood flow information according to an embodiment of theinvention. As seen in FIG. 29, capillary blood flow is in a directionnormal to the surface of sensor array 1220. To separate the capillaryflow from the arteriole flow, multiple apertures of nine elements(3.times.3, 150 micron square) can be selected. This aperture willcreate a very small and close area of sensitivity that can be replicatedin many parts of sensor 1220 simultaneously. The sensitivity of theapertures can be increased by adding the Doppler signals of multipleapertures together. The sensitivity apertures is focused in the firsthalf millimeter of finger 1702 closest to the surface of array 1220.FIG. 30 illustrates a transmitting and/or receiving beam directivitythat can be used to detect capillary blood flow according to anembodiment of the invention.

When using device 1200 to detect blood flow, using a pulsed Dopplerembodiment has the advantage of having the same aperture perform boththe transmit and receive functions. In addition, by gating the receivedsignal, only back-scattered information resulting from a well-definedsample volume is analyzed to obtain the blood flow pattern.

FIG. 31 is a flowchart of a more detailed method 3100 for obtainingbiometric data using device 1200. Method 3100 is described withreference to a particular embodiment of device 1200 having a piezo filmsensor array.

In step 3102, device 1200 is awakened and piezo film sensor array 1220is switched to detect an initial pixel or a group of pixels. Controller1230 switches multiplexers 1225A and 1225B to a designated initial pixelor group of pixels. In one example, piezo film sensor array 1220 is a512.times.512 pixel array. Multiplexers 1225A and 1225B are each used toaddressed and/or select a particular grid line (conductor) at adesignated address of the initial pixel or group of pixels beingdetected.

In step 3104, an input signal is applied to piezo film array 1220. Apulse is applied in one 30 MHZ cycle. Oscillator 1204 generates anoscillation signal at 30 MHZ. Multiplexer 1225A forwards the input pulseto an initial pixel or group of pixels. This input signal is also sentto controller 1230 and output signal processor 1240.

In step 3106, an output signal is obtained from piezo film array 1220.Output signal processor 1240 waits a number of cycles before detecting asignal at the pixel. For example, in response to the signal sent frominput signal generator 1202, output signal processor 1240 waits a numberof cycles after the input pulse is applied to the pixel (or group ofpixels). In step 3108, when the wait is complete, a voltage, forexample, is evaluated using voltage detector 1244.

For example, one 30 MHZ cycle corresponds to approximately 33nanoseconds. The wait can be approximately 5 cycles or 150 nanoseconds.Other wait durations (e.g. a greater or smaller number of periods) canbe used depending upon the oscillator frequency and/or other designconsiderations. This wait allows the ring down oscillation due to thepresence of a fingerprint ridge to occur, in response to the appliedelectrical pulse at the pixel, as described above.

In step 3108, a filtered voltage is evaluated by output signal processor1240 and a grey scale or a binary pixel value is output representativeof the detected voltage (step 3110). A filter circuit (not shown) is aband-pass filter that filters the output voltage to detect an outputvoltage signal in a passband centered about a frequency of approximately30 MHz. The grey scale or binary pixel value is output to memorycontroller 1260 for storage in image memory 1270. In one example, theoutput grey scale or binary pixel value is stored in an address in imagememory 1270 that corresponds to the detected pixel.

In step 3112, a check is made to determine if the scan is complete. Inother words, a check is made to determine whether each pixel in the500.times.400 sensor array 1220 has been scanned and a correspondingoutput value has been stored and accumulated in image memory 1270. Ifthe scan is complete, then the routine ends. A signal or otherindication can then be generated and output from device 1200 toindicate, for example, that a fingerprint image has been successfullycaptured. If the scan is not complete, then the piezo film sensor array1220 is switched to detect the next pixel or next group of pixels (step3114). Control then returns to perform steps 3104 through 3112 at thenext pixel or next group of pixels.

As described above, piezo film sensor array 1220 can be switched bymultiplexers 1225A and 1225B to detect voltage values at a single pixelor a group of pixels. In general, any pattern for scanning pixels can beused. For example, a raster scan of pixels can be performed. Pixels canbe scanned row by row or column by column.

In one preferred example, when multiple groups of pixels are read out ata given instant, each pixel in a group of pixels are separated by apredetermined distance. In this way interfering effects from the ringdown oscillation in neighboring pixels are minimized or avoided. In oneexample, pixels detected in a given cycle are separated by a minimumdistance of at least 8 pixels. In this way any ring down oscillationsbetween neighboring pixels are attenuated significantly.

IV. Example Applications of the Invention

A. Biometric Capture Device

FIG. 32 illustrates a biometric device 3202 according to an embodimentof the invention. Device 3202 has a sensor array 3204 according to theinvention. Device 3202 is particularly adapted for obtaining and storingfingerprint data according to the invention. Device 3202 is intended,for example, to be used by law enforcement personnel.

B. Mobile Biometric Capture Device

FIG. 33 illustrates a mobile biometric device 3300 according to anembodiment of the invention. Device 3300 has a sensor array 3302according to the invention at one end of the device, and a handle 3306at an opposite end. The circuitry of the device is located in a portion3304 of the device. Device 3300 is battery operated. Device 3300 is alsointended, for example, to be used by law enforcement personnel.

C. Wireless Transceiver Biometric Device

FIG. 34 illustrates a wireless transceiver biometric device 3400according to an embodiment of the invention. Device 3400 is intended tobe used by the general populace, for example, as an electronic signaturedevice. Device 3400 has a sensor 3402 for obtaining biometric data, suchas a fingerprint, according to the invention. Device 3400 also is shownas having three indicator lights 3404 for communication information to auser.

FIG. 35 illustrates a more detailed view of the wireless transceiverbiometric device 3400. As can be seen in FIG. 35, sensor 3402 is poweredby a battery 3504. Device 3400 has an antenna 3502 that can be used forsending information to and receiving information from other devices.Device 3400 can be made to be compatible with BLUETOOTH wirelesstechnology. A key ring 3506 can be attached to device 3400. Asillustrated by FIGS. 36 and 37, device 3400 has a multitude of possibleuses.

D. Electronic Sales and/or Transactions

FIG. 36 illustrates using the wireless transceiver biometric device 3400to complete an electronic sales transaction. In step 1 of thetransaction, device 3400 is used to obtain a fingerprint of theindividual wanting to make a purchase. Device 3400 then transmits thefingerprint to a device coupled to cash register 3602 (step 2), whichsends the fingerprint to a third party verification service 3604 (step3). The third party verification service uses the received fingerprintto verify the identity of the purchaser (step 4) by matching thereceived fingerprint to fingerprint data stored in a database. Theidentity of the purchaser can then be sent to cash register 3602 (step5) and to a credit card service 3606 (step 6). The credit card serviceuses the data from the third party verification service to approve salesinformation received from cash register 3602 (step 7) and to prevent theunauthorized use of a credit card. Once cash register 3602 receiveverification of the purchaser's identity and verification that thepurchaser is authorized to use the credit card service, cash register3602 can notify device 3400 to send a credit card number (step 8). Cashregister 3602 can then send the credit card number to the credit cardservice 3606 (step 9), which then transfers money to the sellers bankaccount (step 10) to complete the sales transactions. These steps areillustrative of how device 3400 can be used as an electronic signaturedevice, and are not intended to limit the present invention.

E. Other Wireless Transceiver Biometric Device Applications

FIG. 37 illustrates other applications for which the wirelesstransceiver biometric device 3400 is well suited. For example, device3400 can be used for: building access control; law enforcement;electronic commerce; financial transaction security; tracking employeetime and attendance; controlling access to legal, personnel, and/ormedical records; transportation security; e-mail signatures; controllinguse of credit cards and ATM cards; file security; computer networksecurity; alarm control; and identification, recognition, andverification of individuals. These are just a few of the many usefulapplication of device 3400 in particular, and the present invention ingeneral. Additional applications for device 3400 and the invention willbe apparent to those skilled in the relevant arts given the descriptionof the invention herein.

F. Personal Area Network Applications

As described herein, embodiments of the invention are capable ofinteracting with other devices as part of a personal area network. FIG.38 illustrates one embodiment of a wireless transceiver biometric device3800 according to the invention. Device 3800 comprises a biometricdevice similar to device 1200, described above, a DSP chip 3802, aBLUETOOTH chip 3804, a display 3806, and a battery 3808. As describedabove, device 1200 has a piezo ceramic sensor array 700 and fourmultiplexers 1225 according to the invention.

Biometric device 1200 is coupled to a DSP 3802. DSP 3802 controls device1200 and stores biometric data. DSP 3802 is also coupled to BLUETOOTHchip 3804 for sending and receiving data. A display 3806 is used tocommunicate information to a user of device 3800. Device 3800 is poweredby a battery 3808. As would be known to a person skilled in the relevantart, BLUETOOTH is an agreement that governs the protocols and hardwarefor a short-range wireless communications technology. The invention isnot limited to implementing only the BLUETOOTH technology. Otherwireless protocols and hardware can also be used.

Wireless transceiver biometric device 3800 enables an individual to bein communication with compatible devices within about 30 feet of device3800. Device 3800 can connect, for example, with to telephones, cellphones, personal computers, printers, gas pumps, cash registers,Automated teller machines, door locks, automobiles, et cetera. Becausedevice 3800 can connect to and exchange information or data with anycompatible device within a personal area network, or pico net, device3800 is able to supply a standardized secure identification orauthorization token to any device, or for any process or transactionthat needs or requests it.

G. Public Service Layer Applications

The present invention provides a “public services layer” (PSL) high upin a BLUETOOTH stack. The PSL layer rationalizes identification andaccess control for BLUETOOTH devices communicatively coupled to eachother. In embodiments, the PSL layer supports authorization andidentification based on a fingerprint biometric signal provided by afingerprint scanner. In one example, a wireless transceiver biometricdevice 3800 can be used with a BLUETOOTH module including a BLUETOOTHprotocol stack to provide the fingerprint biometric signal. See, e.g.,the description of BLUETOOTH module, protocol stack, and compliantdevices by Jennifer Bray and Charles Sturman, Bluetooth™ Connect withoutCables, Prentice-Hall, Upper Saddle River, N.J. 2001 (entire bookincorporated in its entirety herein by reference), and Brent Miller andChatschik Bisdikian, Bluetooth Revealed, Prentice-Hall, Upper SaddleRiver, N.J. 2001 (entire book incorporated in its entirety herein byreference).

In embodiments, the PSL layer functionality is defined by a protocol(also called a specification). The PSL layer interprets simple requestsfrom devices in the piconet and acknowledges back with capabilities andlevel of capability in a predefined form. Vendors of BLUETOOTHappliances can add services in the PSL layer of the present invention toenhance the features of their product.

The PSL layer, which would in most cases act transparently to the normalfunction of the device until a PSL request was broadcast that requestedone of the functionality groups that the device supported. One minimumlevel of support rebroadcasts an unsatisfied request in the aid ofextending the scatter net to eventually find a device with the requestedfunction. In this way, other devices outside of the range of arequesting device can be contacted to fulfill the PSL request.

FIG. 39 is a diagram of an example piconet 3900 coupling BLUETOOTHdevices 3910, 39200 according to the present invention. Device BLUETOOTHis a fingerprint scanner with a public service layer and BLUETOOTH stackor chipset. The public service layer can support authorization andidentification. Device 3920 is any BLUETOOTH appliance. Device 3920includes a PSL layer and BLUETOOTH stack or chipset. Piconet 3900 caninclude any number of BLUETOOTH devices within the area of the piconet,within a scatternet, or coupled to the piconet through othercommunication links.

Completing a task may require many functions to be performed in concertamong a constellation of distributed BLUETOOTH appliances. The userwould have to purchase and install sufficient appliances to cover allthe functions in a task. The PSL scheme enables efficiency and costsavings as the appliances would be shared amongst users and in somecases providing multiple uses.

One example operation of the PSL layer is physical access control. APSLlayer of wireless transceiver biometric device 3920 sends or broadcastsone or more request access signals. Such request access signals in thePSL layer can include a request for extract/match/access and datarepresentative of detected fingerprint from outside the securedperimeter via BLUETOOTH. The PSL layer in a Desktop PC with BLUETOOTHinside the secured area receives the request from the wirelesstransceiver biometric device 3920 for extract/match/access and matchesthe print data to the personnel database which could be stored in aserver and sends an access granted to the door. The BLUETOOTH door lockthen opens and the task is completed.

The savings are illustrated by; using a desktop PC that is used forother purposes, to perform the function of access control, time andattendance, personnel tracking and security. The only dedicated hardwareis the BLUETOOTH door lock as the PC and the wireless transceiverbiometric device 3800 are used for other tasks. The installation cost isminimal and the convenience of record keeping and data base managementis also minimal. The three appliances involved in this task could bepurchased from different vendors who have only communicated to the PSLstandard. The function of fingerprint extract/match/access could bepattern, minutiae, local or central or even changed at any time forgreater security and convenience etc, without effecting the door lock orwireless transceiver biometric devices 3800. The turning off or on ofsay lights, air conditioners, telephones, could all be added to thistask if desired.

Another advantage in savings is obsolescence. A building fitted withBLUETOOTH door locks, BLUETOOTH air-conditioning, BLUETOOTH smokedetectors, BLUETOOTH lighting etc. could be upgraded with biometriccontrols without installation costs.

Appliances such a smoke alarms and light fixtures can act as alarms andextend pico nets into scatter nets that will bridge gaps in parks,gardens and car parks adding security an functionality to gates inremote areas.

Telephones could be marketed with BLUETOOTH PSL functionality meaningthat they can dial 911 if an emergency code is received. BLUETOOTH PSLcould signify functionality to be programmed to dial a specific numberfor private emergency services.

Protocols could be defined which log events in a FIFO so false alarmscould be traced and minimized.

In one embodiment, the PSL Specification has the elements identifiedbelow.

A decimal filing system is included. A request is broadcast for afunction that can be as specific as the number of decimal places in therequest. In this way a manufacturer can keep the task in hisconstellation of devices if the devices are available as is expected. Ifthe request is not serviced by the exact function number (FN) requiredthe next nearest FN in the scatter net is used. Clusters of FN are usedaround areas of development.

For example, a light fixture can have a FN of 551.263, which indicates500 a facility utility, 550 a light, 551 a plug in, 551.2 a table lamp,551.26 a halogen low voltage, 551.263 made by a person or company (notexclusive). A request for this specific function of turning on 551.263may be serviced by 557.789 a wall neon as that is all that is availableat the time and the numerically nearest number though limited to thegroup of 55X lighting. The FN 551.26 can be defined in the PSLspecification, digits after this are for manufacturers uses and may beregistered. In this way a lighting manufacturer may supply software fora PC that orchestrates visual effects.

A requesting device or a PSL manager (Piconet Master Device) couldarbitrate in the scatter net to match requests and functions.

The PSL can also define the structure of how functions are allocated. AFN allows one to negotiate with vendors of door locks with minimaleffort. The PSL also give manufacturers of other appliances insight intotask implementation where a wireless transceiver biometric device 3800could play a key roll.

Function Numbers in the PSL are grouped for request and functionsuitability in one example as:

100 Emergency

200 Communications

300 Security

400 Positional

500 Facilities and Utilities

600 Entertainment

700 Computation and Information

800 Transportation

900 Miscellaneous

Sub-functional Groups are defined in one example as follows:

210 Internet connection (for transfer of credentials to local DB)

310 Personal identification via PIN

311 Personal identification via Signature

312 Personal identification via Fingerprint

313 Personal identification via Voice

314 Personal identification via Face

315 Personal identification via Eye

342 Fingerprint Feature Extraction Matching

520 Door Locks

550 Lighting

Requests and Events can also be used in the PSL specification.

Off/ON/More/Less are universal requests. User specific requests wouldnot be in the specification. Events such as ACK, NAC, can also be addedin the PSL specification.

Protocols or the structure of the request and acknowledgment include thefollowing features broadcasted in a packet.

(a) PSL indicates this packet is a PSL function request.

(b) FUNCTION NUMBER indicates the function requested

(c) REQUE indicates the operation to be performed (off/on, lock/unlock)

(d) KEYS authenticates rights of the packet.

(e) PAYLOAD data if applicable

The PSL specification can but does not need to repeat the BLUETOOTHstructure of encryption, error checking et cetera.

The following series of examples serve to illustrate the PSL layer inseveral real-world applications:

Help I have fallen and I can't get up.

a) I press my BLUETOOTH alert button and emergency services arerequested.

b) A PC in the scatter net connects to the world wide web and executes acall to a contracting service supplier (a level one (preferred level)BLUETOOTH service) or in addition to or upon a failure the next leveloccurs.

c) A telephone with BLUETOOTH calls 911 or a service provider with arecorded message (a level two BLUETOOTH service) or upon a failure thenext level occurs.

d) A fire alarm with BLUETOOTH activates (a level three non preferredbut applicable BLUETOOTH service) or upon a failure the next leveloccurs.

e) A smoke detector activates is audio alarm in the hopes of attractingattention (a level four non preferred but applicable BLUETOOTH service)

f) An Automobile within the scatter net activates its horn and flashesits lights to alert personnel to an emergency situation. (a level fivenon preferred but applicable BLUETOOTH service)

I would like access to my office.

a) I press my wireless transceiver biometric device 3800 wirelesstransceiver biometric device 3800.

b) The wireless transceiver biometric device 3800 requests andnegotiates fingerprint identification function from a PC with BLUETOOTHconnected to the server in the office.

c) The server then authorized the door lock with BLUETOOTH to beunlatched.

I would like to get through an airport

a) Baggage check in via kiosk with non reputable ID

b) Seat allocation and gate pass with ID at kiosk

c) Baggage claim with ID

Television programs could broadcast to BLUETOOTH TV that will addeffects to a BLUETOOTH home to assist future versions of Friday the13th.

I would like to make a sizable trade on margin.

a) I verify my identity via wireless transceiver biometric device 3800to my PC

b) The PC requests additional GPS location for the log of the tradeverification.

Other example uses will be apparent to a person skilled in the relevantart given the description of the invention herein. The public servicelayer according to the present invention can be used with any wirelesstransceiver biometric device including any type of fingerprint scanner.For example, fingerprint scanners which can be used include, but are notlimited to, silicon-based fingerprint scanners, optical fingerprintscanners, piezoelectric fingerprint scanners, piezo-film fingerprintscanners and piezo-ceramic fingerprint scanners.

FIG. 40 is an illustration of an interlaced transmit/receive transducer4000 capable of forming the transmitting aperture 2610A and thereceiving aperture 2610B shown in FIG. 27. FIG. 40 is merely oneexemplary embodiment of the aperture 2610B. In FIG. 40, thetransmit/receive aperture array 4000 includes active receivesub-aperture lines 4002 and active transmit sub-aperture lines 4004 on atop side of a transducer sub-structure 4006. Grounding electrodes 4008are formed on a bottom side of the transducer structure 4006.

During operation, the active receive sub-aperture lines 4002 and activetransmit sub-aperture lines 4004 are alternately switched fortransmission and reception in a scanning direction 4010. That is, duringreception, the receive sub-aperture lines 4002 are activated in areceive mode. During transmission, the transmit sub-aperture lines 4004are activated in a transmit mode. Alternately switching, (i.e.,interlacing) the receive sub-aperture lines 4002 and the transmitsub-aperture lines 4004 ensures that each of these is configured todetect the same volume of information related, for example, to obtaincapillary blood flow information.

More specifically, the transducer 4000 illustrated in FIG. 40facilitates near simultaneous transmission and reception sonic waves,representative of blood flow information. In a conventional transducerthat uses the same aperture lines to transmit and receive, there is deadtime between transmitting and receiving. That is, after the transducertransmits, for a few microseconds, it is unable to receive. This deadtime can represent up to several millimeters of tissue depth that cannotbe measured, which ultimately impacts the accuracy of any measurements.

The interlaced transmit/receive transducer 4000 of FIG. 40, however,provides the benefit of two separate transducers using a singletransducer surface (e.g., the top side of the transducer sub-structure4006. In the present invention, the receive sub-aperture lines 4002 canreceive immediately the transmit sub-aperture lines 4004 begintransmitting. This is because each of the electrical channels formed bythe receive sub-aperture lines 4002 and the transmit sub-aperture lines4004 are dedicated to receiving and transmitting, respectively.Consequently, the embodiment of the present invention illustrated inFIG. 40 provides an advantage for near tissue depth imaging.

FIG. 41 is an illustration of a single line swipe fingerprint sensorarray 4100 constructed in accordance with an embodiment of the presentinvention. The single line swipe fingerprint sensor array 4100 of FIG.41 includes a number of sensors 4101 which can number around fourteenhundred, or fewer. As known to those of skill in the art, traditionalswipe sensor arrays typically include fifty thousand or more sensors.The sensor array 4100 is operated by a user moving a biometric digit,such as a finger, from one side 4102 of the of the sensor array 4100 toanother side 4101 of the sensor array 4100.

FIG. 42 is an illustration of an N×M swipe fingerprint sensor array 4200constructed in accordance with another embodiment of the presentinvention. The sensor array 4200 of FIG. 42 facilitates the creation ofoverlapping regions for fingerprint analysis. These overlapping regions,for example, permit the use of fairly complex fingerprint correlationroutines such as those that are based upon Fourier analysis.

FIG. 43 is an illustration of pillar (e.g., sensor) damping as performedin an embodiment of the present invention, such as the N×M sensor array4200 of FIG. 42. More specifically, in the example of FIG. 43, a segment4300 of the sensor array 4200 is shown. The segment 4300 includes, forexample, sensors 4302, 4304, and 4306 of the N×M matrix 4200. Thesegment 4300 of FIG. 3 is provided to show how a transmitted wave can bepartially absorbed into the tissue of a finger to measure acorresponding fingerprint.

In FIG. 43, for example, a fingerprint segment 4308 includes ridges 4310and 4312, and a valley 4314. When the fingerprint segment 4308 comesinto contact with a sensor, (e.g., pillar), such as the sensors 4302,4303, and 4306, this contact creates friction. In air, represented bythe valleys of the fingerprint, such as the valley 4314, this frictionis very low. In tissue, represented by ridges of the fingerprint such asthe ridges 4310 and 4312, the friction is much higher. By applying thefriction to a vibrating sensor, such as one of the sensors 4302, 4304,and 4306, the friction is damped. This damping results in changes in theamplitude and change in its impedance, which can be recorded and used tomeasure the fingerprint. This principle is known to those of skill inthe art, as ringing.

In FIG. 43, this ringing is represented by the length of arrows on topof the sensors 4302, 4304, and 4306, and on the bottom. For example, theridge 4310 is in contact with a surface of the sensor 4302. This contactcreates friction, resulting in ringing. This ringing is damped,represented by shorter arrows 4316. On the other hand, the valley 4314is in close proximity to the surface of the sensor 4304. The sensor 4304has more extensional vibration capability because there is no load, thusno friction to damp its oscillation. This interaction is represented bylonger arrows 4318. The ridge 4312 is in contact with the sensor 4306,whose vibration is dampened by such contact. This damping is againrepresented by shorter arrows 4320. The associated vibration amplitudesare much larger when the sensors 4302, 4304, and 4306 are freelyoscillating in air, rather than being damped by ridges 4308 and 4312.

FIG. 44 is an illustration of an aperture 4400 configured for biplaneimaging in accordance with an embodiment of the present invention. InFIG. 44, orthogonal imaging planes are obtained while switching the roleof an active aperture from top electrodes to bottom electrodes, or viceversa. This switching between top and bottom electrodes creates amulti-dimensional view of, for example, a fingerprint image.

The aperture 4400 includes a transducer structure 4402, and is shownduring exemplary first and second time segments 4404 and 4406,respectively.

During the exemplary first time segment 4404, a group of left mostsub-aperture lines 4407 from among a group of top side aperture lines4408, are configured to actively transmit in a scanning direction 4409.Also, during the first time segment 4404, bottom side sub-aperture lines4410 of the transducer structure 4402, are grounded. Thus, by way ofexample, the first time segment 4404 captures a first snapshot of animage by beginning an active transmission from left to right using thegroup of sub-aperture lines 4408 and grounding the sub-aperture lines4410.

During the second time segment 4406, a group of bottom sub-aperturelines 4412, from among the bottom side aperture lines 4410, areconfigured to actively transmit in a scanning direction 4413. Also,during the second time segment 4406, the top side sub-aperture lines4408 are grounded. Thus, by way of example, the second time segment 4406captures a second snapshot of the image by continuing an activetransmission in an upward and downward manner beginning with the groupof sub-aperture lines 4412 and grounding the sub-aperture lines 4408.

In another ensuing time segments (not shown), a first aperture 4416 ofthe sub-apertures lines 4408, is deactivated and another sub-apertureline 4418, is activated, which facilitates scanning from left to rightalong the scanning direction 4409. During this other ensuing timesegment, all of the bottom side sub-aperture lines 4410 are grounded.This process continues until a final top side sub-aperture line 4420 isactivated, and the process repeats.

Similarly, in yet other time segments (not shown), a first of the bottomside sub-aperture lines 4422 is deactivated and another bottom sidesub-aperture line 4424 is activated. This process continues until afinal bottom side sub-aperture line 4426 is activated, and the processrepeats.

During further periodic time segments (not shown), the aperture 4400 isconfigured to actively receive in a manner identical to the activetransmission process described above.

When sequentially combined, all of the times segments form a bi-planeimaging process. This bi-plane imaging process produces an array thatfacilitates scanning from left to right on the top side of thetransducer structure 4402, also up and down on the bottom side of thetransducer structure 4402. During this process, the grounding roles ofthe sub-aperture lines 4408 and 4410 are reversed. This process providesa multi-dimensional view of an image, for example, of a fingerprint. Atthe same time, it simplifies the transducer and reduces the amount ofelectronics required for construction, ultimately reducing transducercosts.

FIG. 45 is an illustration 4500 depicting linear electronic switchingscans in an azimuthal direction 4502 in accordance with an embodiment ofthe present invention. More specifically, in the illustration 4500, ascanning beam moves along the azimuthal direction 4502 in a sequentialmanner.

In FIG. 45, an aperture structure 4504 includes sub-aperture lines 4506on a top side and sub-aperture lines 4508 on a bottom side. In theembodiment of FIG. 45. the sub-aperture lines 4508 on the bottom sideare all connected to ground. In operation during a first time segment4510, selected adjacent ones of the sub-aperture lines 4506 are used toform a sub-aperture 4512. By way of example, during this first timesegment 4510, the first sub-aperture 4512 is used to form a scanningbeam that collects biometric data, such as a portion of a fingerprint,during a first scan. During this first scan, the beam uses the collecteddata to form a first image and then switches to an ensuing beam duringan ensuing time segment 4514.

During the ensuing time segment 4514, different adjacent selected onesof the sub-aperture lines 4506 are used to form a sub-aperture 4516.That is, during the time segment 4514, the aperture structure 4510switches to the next beam. More specifically, during the time segment4514, the sub-aperture 4516 forms another beam which representsazimuthal movement of the scan along the direction 4502 (i.e., from leftto right). This process repeats until during a time segment 4518, afinal sub-aperture 4520 is formed that includes final adjacent selectedones of the sub-aperture lines 4506 which combine to form a finalscanning beam. Although three lines are used in the examples ofsub-apertures 4512, 4516, and 4520, in practice any suitable number ofsub-aperture lines can be used.

CONCLUSION

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedin the appended claims. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What we claim is:
 1. A transmitting and receiving sonic transducer,comprising: a two dimensional array of sensor elements, wherein eachsensor element within said array is separately addressable viaelectronic control; and wherein each sensor element is capable oftransmitting during a first time interval and alternatively receivingduring a second time interval, as directed via said electronic control;and wherein a first set of sensor elements are selected to form a firstpattern within said array and a second set of elements are selected toform a second pattern within said array; and wherein said first patternand said second pattern each form groups of sensor elements that aremutually exclusive and that are proximate to each other; and whereincontrol electronics are configured to control said first set of sensorelements to transmit and to not receive during a first set of one ormore selected time intervals, and said control electronics areconfigured to control said second set of sensor elements to receive andto not transmit during a second set of one or more selected timeintervals, and wherein said first set of selected time intervals to notoverlap in time with any of said second set of time intervals.
 2. Thetransducer of claim 1 wherein said first pattern is a contiguous seriesof sensor elements and said second pattern is a contiguous series ofsensor elements.
 3. The transducer of claim 2 wherein said first patternforms at least one straight line of sensor elements and said secondpattern forms at least one straight line of sensor elements.
 4. Thetransducer of claim 3 where in at least one straight line formed by saidfirst pattern is adjacent to at least one straight line formed by saidsecond pattern.
 5. The transducer of claim 3 where each straight lineformed by said first pattern is adjacent to at least one straight lineformed by said second pattern.
 6. The transducer of claim 3 wherein saidlines of said first pattern are interlaced with said lines of saidsecond pattern.
 7. An apparatus for transmitting and receiving sonicenergy, comprising a two dimensional array of sensor elements, whereineach sensor element within said array is separately addressable viaelectronic control; and wherein each sensor element is capable oftransmitting during a first time interval and alternatively receivingduring a second time interval, as directed via said electronic control;and wherein a first set of sensor elements are selected to form a firstpattern within said array and a second set of elements are selected toform a second pattern within said array; and wherein said first patternand said second pattern each form groups of sensor elements that aremutually exclusive and that are proximate to each other; and whereincontrol electronics are configured to control said first set of sensorelements to transmit and to not receive during a first set of one ormore selected time intervals, and said control electronics areconfigured to control said second set of sensor elements to receive andto not transmit during a second set of one or more selected timeintervals, and wherein at least one of said second set of sensorelements receives immediately as at least one of said first set ofsensor elements begins transmitting.
 8. The apparatus of claim 7 whereinsaid first pattern is a contiguous series of sensor elements and saidsecond pattern is a contiguous series of sensor elements.
 9. Theapparatus of claim 8 wherein said first pattern forms at least onestraight line of sensor elements and said second pattern forms at leastone straight line of sensor elements.
 10. The apparatus of claim 9 wherein at least one straight line formed by said first pattern is adjacentto at least one straight line formed by said second pattern.
 11. Theapparatus of claim 9 where each straight line formed by said firstpattern is adjacent to at least one straight line formed by said secondpattern.
 12. The apparatus of claim 9 wherein said lines of said firstpattern are interlaced with said lines of said second pattern.
 13. Theapparatus of claim 7 wherein said first pattern elements are activatedin sequence along a scanning direction.
 14. The apparatus of claim 7wherein said first pattern elements and said second pattern elementsalternately switched along a scanning direction.
 15. A system fortransmitting and receiving sonic energy, comprising a two dimensionalarray of sensor elements, wherein each sensor element within said arrayis separately addressable via electronic control; and wherein eachsensor element is capable of transmitting during a first time intervaland alternatively receiving during a second time interval, as directedvia said electronic control; and wherein a first set of sensor elementsare selected to form a first pattern within said array and a second setof elements are selected to form a second pattern within said array; andwherein said first pattern and said second pattern each form groups ofsensor elements that are mutually exclusive and that are proximate toeach other; and wherein control electronics are configured to controlsaid first set of sensor elements to transmit and to not receive duringa first set of one or more selected time intervals, and said controlelectronics are configured to control said second set of sensor elementsto receive and to not transmit during a second set of one or moreselected time intervals, and wherein at least one of said second set ofsensor elements receives immediately as at least one of said first setof sensor elements begins transmitting.
 16. The system of claim 15wherein said first pattern is a contiguous series of sensor elements andsaid second pattern is a contiguous series of sensor elements.
 17. Thesystem of claim 16 wherein said first pattern forms at least onestraight line of sensor elements and said second pattern forms at leastone straight line of sensor elements.
 18. The system of claim 17 wherein at least one straight line formed by said first pattern is adjacentto at least one straight line formed by said second pattern.
 19. Thesystem of claim 17 where each straight line formed by said first patternis adjacent to at least one straight line formed by said second pattern.20. The system of claim 17 wherein said lines of said first pattern areinterlaced with said lines of said second pattern.
 21. The system ofclaim 15 wherein said first pattern elements are activated in sequencealong a scanning direction.
 22. The system of claim 15 wherein saidfirst pattern elements and said second pattern elements alternatelyswitched along a scanning direction.
 23. A method for transmitting andreceiving sonic energy, comprising the steps of: providing a twodimensional array of sensor elements, wherein each sensor element withinsaid array is separately addressable via electronic control; and whereineach sensor element is capable of transmitting during a first timeinterval and alternatively receiving during a second time interval, asdirected via said electronic control; and selecting a first set ofsensor elements to form a first pattern within said array and selectinga second set of elements to form a second pattern within said array; andwherein said first pattern and said second pattern each form groups ofsensor elements that are mutually exclusive and that are proximate toeach other; and providing control electronics configured to control saidfirst set of sensor elements to transmit and to not receive during afirst set of one or more selected time intervals, and configured tocontrol said second set of sensor elements to receive and to nottransmit during a second set of one or more selected time intervals, andwherein at least one of said second set of sensor elements receivesimmediately as at least one of said first set of sensor elements beginstransmitting.
 24. The method of claim 23 wherein said first pattern is acontiguous series of sensor elements and said second pattern is acontiguous series of sensor elements.
 25. The method of claim 24 whereinsaid first pattern forms at least one straight line of sensor elementsand said second pattern forms at least one straight line of sensorelements.
 26. The method of claim 25 where in at least one straight lineformed by said first pattern is adjacent to at least one straight lineformed by said second pattern.
 27. The method of claim 25 where eachstraight line formed by said first pattern is adjacent to at least onestraight line formed by said second pattern.
 28. The method of claim 25wherein said lines of said first pattern are interlaced with said linesof said second pattern.
 29. The method of claim 23 wherein said firstpattern elements are activated in sequence along a scanning direction.30. The method of claim 23 wherein said first pattern elements and saidsecond pattern elements alternately switched along a scanning direction.